In mobile communication which is becoming widely used in recent years, communication schemes with different systems are adopted by a plurality of communication business companies, such as an NTT scheme, J-TACS scheme, N-TACS scheme, GSM scheme, PDC scheme, etc. Then, when a mobile subscriber moves to another business company's service area, the so called roaming operation is provided as a service for enabling calling and call receiving from that service area using a different system.
For this roaming which enables the call termination connection regardless of where the mobile subscriber is located, the following two schemes are conventionally known. Namely, a scheme in which a visited location register of a visited network temporarily allocates a roaming number at a time of call termination connection, and a scheme in which a gateway location register of a visited network allocates a roaming number at a time of position registration.
First, the former one of the conventionally known schemes described above, that is a scheme in which a visited location register of a visited network temporarily allocates a roaming number at a time of call termination connection, will be described. In order to describe this scheme, a configuration of a mobile communication system is shown in FIG. 1, and its control methods are shown in FIG. 2 and FIG. 3. In each of these figures, VMSC (Visited Mobile Switching Center) is a visited mobile switching center, VLR (Visited Location Register) is a visited location register, HLR (Home Location Register) is a home location register, and GMSC (Gateway Mobile Switching Center) is a gateway mobile switching center. Also, a solid line indicates a communication channel, and a dashed line indicates a control channel.
As shown in FIG. 2, when a mobile subscriber moves (1) to a control area of some visited mobile switching center VMSC2, a position registration request (2) is made with respect to the visited mobile switching center VMSC2. When the position registration request (2) is received, the visited mobile switching center VMSC2 carries out a position registration request (3) with respect to a visited location register VLR2. When the position registration request (3) is received, the visited location register VLR2 normally searches an information of that mobile subscriber and updates a position information. However, the visited location register VLR2 does not store an information of a subscriber who requested the position registration for the first time, so that a region for storing an information of that subscriber is secured, and a position information of that subscriber is stored. In addition, the visited location register VLR2 notifies (4) an ID number of the visited mobile switching center VMSC2 and an ID number of the visited location register VLR2 to a home location register HLR which constantly stores the subscriber information of that subscriber. The home location register HLR stores (5) these visited mobile switching center ID number and visited location register ID number.
Next, when a received call for the mobile subscriber occurs, as shown in FIG. 3, this received call is routed as an IAM (Initial Address Message) to a gateway mobile switching center GMSC of the mobile communication network to which this subscriber is subscribing, according to the subscriber number of that subscriber. The gateway mobile switching center GMSC requests (2) an information for routing the received call to that mobile subscriber, with respect to the home location register HLR. When the routing information request (2) from the gateway mobile switching center GMSC is received, the home location register HLR searches an information of that subscriber, and learns the ID number of the visited mobile switching center VMSC2 and the ID number of the visited location register VLR2. In addition, the home location register HLR requests (3) an allocation of a roaming number for the purpose of routing the received call of that subscriber to the visited mobile switching center, with respect to the visited location register VLR2. When the roaming number allocation request (3) is received, the visited location register VLR2 temporarily allocates (4) a roaming number to that subscriber, and returns (5) it to the home location register HLR. The home location register HLR notifies (6) the roaming number to the gateway mobile switching center GMSC. The gateway mobile switching center GMSC routes (7) the received call as the IAM to the visited mobile switching center VMSC2 according to the roaming number.
Next, the latter one of the conventionally known schemes described above, that is a scheme in which a gateway location register of a visited network allocates a roaming number at a time of position registration, will be described. In order to describe this scheme, a configuration of a mobile communication system is shown in FIG. 4, and its control methods are shown in FIG. 5 and FIG. 6. In each of these figures, GLR (Gateway Location Register) is a gateway location register.
Note that, as long as the mobile subscriber moves within the subscribed mobile communication network, the position information of that subscriber is updated at each home location register HLR. However, in order for the mobile subscriber to make a communication by moving to the not subscribed mobile communication network, it is necessary for the mobile subscriber to make a roaming contract with that mobile communication network in advance.
As shown in FIG. 5, when a mobile subscriber 60 moves (1) to that roaming contracted mobile communication network 11, a position registration request (2) is made with respect to the visited mobile switching center VMSC44 of that mobile communication network 11. When the position registration request (2) is received, the visited mobile switching center VMSC44 carries out a position registration request (3) with respect to a gateway location register GLR31. When the position registration request (3) is received, the gateway location register GLR31 does not store an information of a subscriber who requested the position registration for the first time, so that a region for storing an information of that subscriber is secured, and a roaming number is allocated (4) to that subscriber. In addition, the gateway location register GLR31 notifies (5) the roaming number to a home location register HLR20 which constantly stores the subscriber information of that subscriber, and the home location register HLR20 stores (6) this roaming number.
Next, when a received call for the mobile subscriber 60 occurs, as shown in FIG. 6, this received call is routed (1) as an IAM to a gateway mobile switching center GMSC50 of the mobile communication network 10 to which this subscriber is subscribing, according to the subscriber number of that subscriber. The gateway mobile switching center GMSC50 requests (2) an information for routing the received call to that mobile subscriber 60, with respect to the home location register HLR20.
When the routing information request (2) from the gateway mobile switching center GMSC50 is received, the home location register HLR20 searches an information of that subscriber, and when the roaming number is stored, returns (3) this roaming number to the gateway mobile switching center GMSC50. The gateway mobile switching center GMSC50 routes (4) the received call as the IAM to the gateway mobile switching center GMSC51 of the mobile communication network 11 visited by that subscriber, according to this roaming number. The gateway mobile switching center GMSC51 of the mobile communication network 11 visited by that subscriber requests (5) an information for routing the received call to that mobile subscriber, with respect to the gateway location register GLR31. The gateway location register 31 returns (6) the position information of that subscriber to the gateway mobile switching center GMSC 51. The gateway mobile switching center GMSC51 terminates the call to the mobile subscriber 60 by carrying out the paging according to the received position information.
However, in the conventional schemes described with references to FIG. 1 to FIG. 6 described above, when the mobile subscriber roams between a communication network (FIG. 1 to FIG. 3) adopting a scheme in which a visited location register of a visited network (that is a roaming destination mobile communication network) temporarily allocates a roaming number at a time of call termination connection, and a mobile communication network (FIG. 4 to FIG. 6) adopting a scheme in which a gateway location register of a visited network allocates a roaming number at a time of position registration, because the roaming number allocation schemes are different in these mobile communication networks, there is no method for allocating the roaming number to that mobile subscriber, and as a result, there has been a drawback that the mobile subscriber cannot roam.
On the other hand, the conventional roaming includes a personal roaming which is realized only between the mobile communication networks supporting a personal mobile communication in which a subscriber number assigned to a user and a mobile terminal number assigned to a mobile terminal are arbitrarily set in correspondence.
With reference to FIG. 7, a personal roaming control scheme for carrying out the personal roaming in such personal mobile communication networks will be described.
In FIG. 7, a mobile communication network 411 which is supporting the personal mobile communication scheme has a user home location register HLR-P (Home Location Register for Personal mobility) 412 for holding a subscriber information P-data4 which is identified by a subscriber number PID4, and a mobile terminal home location register (Home Location Register for Terminal mobility) 413 for holding a mobile terminal information T-data4 of a mobile terminal which is identified by a mobile terminal number TID4, while a mobile communication network 111 which is supporting the personal mobile communication scheme has a user gateway location register GLR-P (Gateway Location Register for Personal mobility) 112 for holding a subscriber information R-P-data1 for a roaming user which is identified by a subscriber number PID4, and a mobile terminal home location register (Home Location Register for Terminal mobility) 113 for holding a mobile terminal information T-data1 of a mobile terminal which is identified by a mobile terminal number TID1.
In FIG. 7, when a user of the mobile communication network 411 moves (S31) to the mobile communication network 111, in order to realize the roaming to that mobile communication network 111, it is necessary to notify and register (S32) the subscriber number PID4 and the mobile terminal number TID1 of the mobile terminal 115 to the mobile communication network 111 which is the roaming destination network. Note that, in this case, as a means for enabling the user to notify the subscriber number PID4 to the mobile communication network 111 through the mobile terminal 115, it is possible to consider a method in which the user owns a user device which stores the subscriber number PID4, and the subscriber number PID4 is automatically notified to the mobile communication network 111 when that user device is attached to the mobile terminal 115 of the mobile communication network 111 which is the roaming destination network. Alternatively, as another means, a method in which the user explicitly notifies it to the mobile communication network 111 which is the roaming destination network by using dials, etc. is also possible.
By such means, when the user notifies the subscriber number PID4 and the mobile terminal number TID1 through the mobile terminal 115 to the mobile communication network 111 which is the roaming destination network, a combination of the subscriber number PID4 and the mobile terminal number TID1 is registered (S33) in the user gateway location register 112 of the mobile communication network 111. Then, the user gateway location register 112 inquires (S34) the subscriber information to the user home location register 412 of the mobile communication network 411 which is the user's home network, by using the subscriber number PID4 as a key. In response to this inquiry, the user home location register 412 outputs the subscriber information P-data4, and the mobile communication network 111 registers (S35) that subscriber information P-data4 as the roaming subscriber information R-P-data1 into the user gateway location register 112 in correspondence to the subscriber number PID4.
By the above processing, the subscriber information of the user of the mobile communication network 411 is transferred to the mobile communication network 111, so that it becomes possible for that user to make a call in the mobile communication network 111, and the personal roaming is completed.
In this manner, the personal roaming control can be carried out between the mobile communication networks supporting the personal mobile communication scheme, but in a case where the user's home network does not have a personal mobile communication function, even when the gateway location register GLR-P of the roaming destination network directly inquires the home location register HLR of the user's home network, it is impossible to make a response by taking out only the subscriber information because the subscriber information and the mobile terminal information is integrally provided in that home location register, and there has been a problem that the personal roaming cannot be made.